Edexcel GCSE Combined Science key terms

Plant transport tissue containing living cells that use energy to transport sucrose around a plant.

The process by which plants and algae use light energy to convert carbon dioxide and water into glucose, releasing oxygen.

A structure that blocks pathogen entry or traps and removes pathogens.

A change in which no new substance is formed. Reversing a change of state restores the material's original properties.

A measurable property, such as mass, time or electric current, expressed using a numerical value and a unit.

The form of a substance: solid, liquid or gas, at a stated temperature.

A biological extraction method in which plants absorb metal ions through their roots and are harvested and burned to produce ash containing metal compounds.

A unit of length equal to $10^{-12}$ metres. Its symbol is pm.

A treatment containing no active drug, used as a comparison in a clinical trial.

The liquid component of blood in which blood cells and platelets are suspended and many transported substances are dissolved.

A small circular molecule of DNA found in bacteria, separate from their main chromosome.

A flat section of a graph. On a temperature–time graph for melting ice, it shows that the temperature remains approximately constant during melting.

A cell fragment involved in blood clotting, helping prevent blood loss and the entry of microorganisms through wounds.

A small compass whose freely turning magnetic needle shows the direction of the magnetic field at its position.

An atomic model in which negatively charged electrons are embedded in a sphere of spread-out positive charge.

A group of two or more atoms with an overall electrical charge, treated as one unit when balancing an ionic formula.

The inheritance of a characteristic controlled by more than one gene.

A very large molecule made from many smaller units joined together by covalent bonds.

A group of organisms of the same species living in the same place at the same time.

The number of organisms per unit area, for example plants per square metre.

The number of organisms of one species living in a defined area.

The relative concentrations of reactants and products in a mixture at equilibrium.

A relationship in which two measured quantities tend to increase together or decrease together. This alone does not establish that one causes the other.

An atom that has lost one or more electrons and therefore has more protons than electrons.

A particle with the same mass as an electron but an equal and opposite positive charge.

Water that is safe to drink; it need not be chemically pure.

The energy transferred per unit charge between two points in a circuit, measured in volts (V). It is also called voltage.